LONDON — Former Barclays PLC Chief Executive Robert Diamond has given up bonuses of up to $31 million in an apparent effort to shield the lender as the bank looks to defuse political anger following the rate-fixing scandal.

Barclays Chairman Marcus Agius told British lawmakers Tuesday that Mr. Diamond had voluntarily given up the long-term pay incentive as the bank came under renewed pressure over the affair. He added that the board “welcomed” the move.

Mr. Agius disclosed Mr. Diamond’s deferred bonuses Tuesday before a U.K. parliamentary committee that is probing attempts by Barclays and, allegedly, other banks to try and manipulate the London interbank offered rate, or Libor.

Barclays Chairman Marcus Agius appearing before U.K. lawmakers announced that the former CEO Robert Diamond will forgo deferred bonuses valued up to $31 million.

Barclays recently paid $450 million to settle an investigation into attempts by bank staff to fix the benchmark rates.